This invention relates to anti-bonding methods for blast furnace slag or its grading adjusted slag. From the point of view of the protection of natural resources now that the exhaustion of natural sand is becoming a serious problem in recent years, blast furnace slag and its grading adjusted slag obtained by crashing it and sorting it according to the particle size (hereinafter referred to together as the “blast furnace slag materials”) are coming to be substituted more and more frequently for natural sand to be used in civil engineering projects and as fine aggregates for the production of concrete. Such blast furnace slag materials are frequently left piled up outdoors while waiting to be shipped or transported on a cargo boat over a long period of time. When they are thus left stored or transported over a long period of time, they tend to bond together, or to become consolidated, and may eventually become like blocks of rock. This phenomenon is particularly prominent in summer months when the temperature is high. Consolidated blast furnace slag materials cannot be used as a substitute for natural sand. An enormous labor would be required if it were attempted to forcibly use such consolidated blast furnace slag materials as a substitute of natural sand. Thus, it is a requirement to keep blast furnace slag materials from bonding or consolidating while they are being stored or transported over a long period of time if they are to be used as a substitute for natural sand. It is therefore an object of this invention to provide anti-bonding agents and methods for such blast furnace slag materials.
Examples of prior art anti-bonding agent for blast furnace slag materials include aliphatic hydroxycarboxylic acids and their salts (Japanese Patent Publication Tokkai 54-130496), lignin sulfonic acids and their salts (Japanese Patent Publication Tokkai 57-95857), saccharides (Japanese Patent Publication Tokkai 58-104050) and alkylene oxide adducts of aliphatic hydroxycarboxylic acids and their salts (Japanese Patent Publication Tokkai 2001-58855). These anti-bonding agents are usually used by preparing an aqueous solution diluted with water and applying it, say, by spraying it, on the blast furnace slag materials. Some of these prior art anti-bonding agents are more effective than the others but their anti-bonding effects are generally insufficient. Since the water retentivity of these blast furnace slag materials is generally low, it may be that the anti-bonding agent applied on them may flow away with the water used for diluting or rainwater such that the expected anti-bonding effect is not always obtained. Moreover, some prior art anti-bonding agents are said to adversely affect the strength of the hardened objects if the blast furnace slag material on which they are applied is used as fine aggregates in the production of concrete.